1. Field of the Invention
The present invention relates to a magnetic sensor, and more particularly, to a magnetic sensor having a soft magnetic body that converts a magnetic field component in a vertical direction into a magnetic field component in a horizontal direction.
2. Description of the Related Art
A magnetic sensor using a magneto resistive effect element can be used as a geomagnetic sensor that is incorporated in, for example, a mobile device such as a mobile phone or a smartphone and detects geomagnetism. The geomagnetic sensor is configured so as to be able to detect each of magnetic field components in an X-axis direction and a Y-axis direction orthogonal to each other in a horizontal plane and a vertical direction (Z-axis direction) orthogonal to the horizontal plane.
International Publication No. WO2011/068146 describes a magnetic sensor capable of detecting a magnetic field component in a vertical direction. However, in the magnetic sensor described in International Publication No. WO2011/068146, it is necessary for an aspect ratio (height dimension/width dimension) of a soft magnetic body that converts a magnetic field in a vertical direction into a magnetic field in a horizontal direction to be increased from 1.5 times to approximately 4 times. Therefore, a case where a strong magnetic field is applied from the outside, a magnetization direction of the soft magnetic body is directed in a height direction and residual magnetization occurs in the height direction of the soft magnetic body. Accordingly, a problem is caused in that a hysteresis of a BH curve in the height direction of the soft magnetic body increases, and sensor sensitivity is degraded due to occurrence of an offset of the magnetic sensor, or the like.
As a magnetic sensor capable of solving such a problem, Japanese Unexamined Patent Application Publication No. 2015-203647 describes a magnetic sensor including a magneto resistive effect element formed on a substrate, and a pair of soft magnetic bodies extending in a direction away from a surface of the substrate on which the magneto resistive effect element is formed, wherein when orthogonal directions in an plane of the substrate are a first direction and a second direction, the magneto resistive effect element includes a fixed magnetic layer of which a magnetization direction is fixed and a free magnetic layer of which a magnetization direction is changed by an external magnetic field, the magnetization direction of the fixed magnetic layer is directed in the first direction, the magneto resistive effect element is provided at a position where a center position in the first direction of the pair of soft magnetic bodies and a center position in the first direction of the magneto resistive effect element do not overlap, on lower surface sides of the pair of soft magnetic bodies, and the pair of soft magnetic bodies are spaced apart from each other in the first direction and face, and are connected to each other on the lower surface sides of the pair of soft magnetic bodies.
According to the magnetic sensor described in Japanese Unexamined Patent Application Publication No. 2015-203647, a pair of soft magnetic bodies are provided, and a magnetic path is formed from an upper surface side of one of the soft magnetic body to an upper surface side of the other soft magnetic body via a lower surface side of the one soft magnetic body. Therefore, even in a case where a strong external magnetic field is applied, it is difficult for a magnetization direction of the pair of soft magnetic bodies to be directed in a height direction and it is difficult for residual magnetization to occur in the height direction of the pair of soft magnetic bodies. Thus, it is possible to suppress an increase in hysteresis of the pair of soft magnetic bodies. Therefore, it is possible to convert a magnetic field component in a vertical direction into a magnetic field component in an in-plane direction of the substrate using the pair of soft magnetic bodies, and to suppress a degradation of sensitivity due to occurrence of an offset of the magnetic sensor, or the like, and obtain good sensor sensitivity.
In the magnetic sensor described in Japanese Unexamined Patent Application Publication No. 2015-203647, since residual magnetization hardly occurs in the height direction of a pair of soft magnetic bodies as described above, it is possible to have good sensor sensitivity. However, in the magnetic sensor described in Japanese Unexamined Patent Application Publication No. 2015-203647, an influence of a change in a relative position between the pair of soft magnetic bodies and the magneto resistive effect element on intensity of a magnetic field applied to the magneto resistive effect element is great, as described below. Therefore, in the magnetic sensor described in Japanese Unexamined Patent Application Publication No. 2015-203647, it is clear that sufficiently high shape accuracy or arrangement accuracy of each component is required in order to appropriately exhibit original functions of the magnetic sensor.